Magnetic resonance imaging apparatus and scanning-condition setting method

ABSTRACT

According to a Magnetic Resonance Imaging (MRI) apparatus, a scanning-parameter limit calculating unit creates examination information that represents scanning conditions for collection of magnetic resonance signal data based on scanning parameters set by an operator; a scanning-condition edit/scan positioning unit creates a time chart that indicates the type and a sequential execution order of an event to be executed when collecting magnetic resonance signal data based on the examination information created by the scanning-parameter limit calculating unit, and causes a time-chart display unit to display the created time chart.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is divisional of U.S. patent application Ser. No.13/646,205 filed on Oct. 5, 2012, which is a continuation of U.S. patentapplication Ser. No. 12/413,520 filed on Mar. 28, 2009 and issued asU.S. Pat. No. 8,842,895 on Sep. 23, 2014, which is based upon and claimsthe benefit of priority from the prior Japanese Patent Application No.2008-93233, filed on Mar. 31, 2008; the entire contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic resonance imaging apparatusthat takes an image of a subject by collecting data about the inside ofthe subject by using magnetic resonance phenomenon, and ascanning-condition setting method.

2. Description of the Related Art

Conventionally, a magnetic resonance imaging apparatus is an apparatusthat images an arbitrary cross section of a subject, such as a humanbody, by using various contrasts between tissues. Such magneticresonance imaging apparatus performs imaging by executing a procedureso-called a pulse sequence, which sequentially defines eventsrepresenting timing of application of a radio-frequency pulse or agradient magnetic field pulse, and timing of data collection.

An operator of the magnetic resonance imaging apparatus appropriatelysets various scanning parameters prior to a scan, and obtainsinformation required for an examination, such as contrast, Signal toNoise ratio (SN ratio), spatial resolution, flow velocity, anddiffusion. The scanning parameters include, for example, a RepetitionTime (TR), Echo Time (TE), the number of matrices, Field of View (FOV),the number of slices, and slice thickness.

FIG. 11 is a schematic diagram that depicts an example of a userinterface for editing scanning parameters according to a conventionalmagnetic resonance imaging apparatus. FIG. 11 depicts ascanning-condition edit screen including various scanning parameters asedit items. The operator sets a value of a required scanning parameterby inputting a numerical value or operating a user interface, such as aslider or a button, on the scanning-condition edit screen shown in FIG.11.

Additionally to the scanning parameters described above, the operatoredits scanning conditions, such as an imaging method (type of pulsesequence, for example, spin echo, or Echo Planar Imaging (EPI)), thetype of a prepulse, such as a fat suppression pulse or an inversionpulse, the number of prepulses, the order of prepulses, and the order ofslice excitation, in accordance with a purpose. As a technology forconfirming spatial arrangement of such prepulses and scanning pulses,there is a technology of displaying a slice region on a positioningimage (for example, see JP-A 2003-290171 (KOKAI)). A positioning imageused in the technology is called a graphic locator, for example.

However, according to the conventional technology described above, theoperator can confirm spatial arrangement of a prepulse or a scanningpulse, but cannot confirm temporal order of the prepulses or thescanning pulses. In other words, according to the conventionaltechnology, when changing a scanning condition, the operator cannotobtain information that influences an image to be obtained, for example,timing of collection of data at a target scan position, the type of eachprepulse to be applied, the order and the frequency of application ofprepulses.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a magnetic resonanceimaging apparatus includes a scanning-condition creating unit thatcreates examination information that represents a scanning condition forcollection of data indicating an inside of a subject, based on a valueof a scanning parameter set by an operator; a chart display-control unitthat creates and causes a display unit to display a time chart thatindicates a type and a sequential execution order of an event to beexecuted when performing the collection of data, based on theexamination information created by the scanning-condition creating unit;a data collecting unit that collects data indicating the inside of thesubject by using the examination information created by thescanning-condition creating unit; and an image reconstructing unit thatreconstructs an image from the data collected by the data collectingunit.

According to another aspect of the present invention, ascanning-condition setting method of a magnetic resonance imagingapparatus, includes creating examination information that represents ascanning condition for collection of data indicating an inside of asubject based on a value of a scanning parameter set by an operator; andcreating and causing a display unit to display a time chart indicating atype and a sequential execution order of an event to be executed whenperforming the collection of data, based on the created examinationinformation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a general configuration of an MRIapparatus according to an embodiment of the present invention;

FIG. 2 is a functional block diagram of a detailed configuration of acomputing system according to the embodiment;

FIG. 3 is a schematic diagram for explaining display of a time chartconducted by a scanning-condition edit/scan positioning unit;

FIG. 4 is a schematic diagram for explaining display of the time chartwhen a presat button is pressed;

FIGS. 5A and 5B are schematic diagrams for explaining display of thetime chart when an interleave button is pressed;

FIG. 6 is a flowchart of a process procedure of time-chart displayperformed by the MRI apparatus according to the embodiment;

FIG. 7 is a schematic diagram of an example of a time chart according tothe embodiment for coronary angiography combined with Electrocardiogram(ECG) gating;

FIG. 8 is a schematic diagram of an example of a time chart according tothe embodiment for imaging by a segmented field echo method;

FIGS. 9A and 9B are schematic diagrams of an example of a time chartaccording to the embodiment for imaging by Time Spatial LabelingInversion Pulse (Time-SLIP) method;

FIGS. 10A, 10B, and 10C are schematic diagrams of an example of a timechart when displaying the position of collected data in a k-space; and

FIG. 11 is a schematic diagram of an example of a user interface forediting scanning parameters according to a conventional magneticresonance imaging apparatus.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of a magnetic resonance imaging apparatus and ascanning-condition setting method according to the present inventionwill be explained below in detail with reference to the accompanyingdrawings. A Magnetic Resonance Imaging apparatus is referred to as anMRI apparatus in the following embodiments.

First of all, a general configuration of an MRI apparatus according toan embodiment of the present invention is explained below with referenceto FIG. 1. FIG. 1 is a schematic diagram of a general configuration ofan MRI apparatus 100 according to the embodiment. As shown in FIG. 1,the MRI apparatus 100 includes a static magnetic-field magnet 1, agradient magnetic-field coil 2, a gradient magnetic-field power source3, a patient couch 4, a patient couch control unit 5, a Radio Frequency(RF) transmitting coil 6, a transmitting unit 7, a RF receiving coil 8,a receiving unit 9, and a computing system 10.

The static magnetic-field magnet 1 is formed in a hollow cylindricalshape, and generates a uniform static magnetic field in a space itsinside. For example, a permanent magnet, or a super conducting magnet isused as the static magnetic-field magnet 1.

The gradient magnetic-field coil 2 is formed in a hollow cylindricalshape, and is arranged inside the static magnetic-field magnet 1. Thegradient magnetic-field coil 2 is formed of three coils in combinationcorresponding to x, y, and z axes orthogonal to one another. The threecoils generate gradient magnetic fields along three directions of the x,y, and z axes, respectively, by individually receiving a current supplyfrom the gradient magnetic-field power source 3. It is assumed that thez axis direction is the same direction as the static magnetic field.

The gradient magnetic fields of the x, y, and z axes generated by thegradient magnetic-field coil 2 correspond to, for example, aslice-selective gradient magnetic field Gs, a phase encoding gradientmagnetic field Ge, and a readout gradient magnetic field Gr,respectively. The slice-selective gradient magnetic field Gs is used forarbitrarily setting a scan cross section. The phase encoding gradientmagnetic field Ge is used for changing a phase of a magnetic resonancesignal in accordance with a spatial position. The readout gradientmagnetic field Gr is used for changing the frequency of a magneticresonance signal in accordance with a spatial position.

The gradient magnetic-field power source 3 supplies a current to thegradient magnetic-field coil 2 based on pulse-sequence execution datasent from the computing system 10.

The patient couch 4 includes a top plate 4 a on which a subject P is tobe placed. Under the control of the patient couch control unit 5, thepatient couch 4 inserts the top plate 4 a on which the subject P isplaced, into a hole (a scanning space) of the gradient magnetic-fieldcoil 2. Usually, the patient couch 4 is placed such that thelongitudinal direction of the patient couch 4 is to be parallel to thecentral axis of the static magnetic-field magnet 1.

The patient couch control unit 5 controls the patient couch 4. Thepatient couch control unit 5 moves the top plate 4 a in the longitudinaldirection and upward and downward directions by driving the patientcouch 4.

The RF transmitting coil 6 is arranged inside the gradientmagnetic-field coil 2, and generates an RF magnetic field by receivingsupply of a radio-frequency pulse from the transmitting unit 7.

The transmitting unit 7 sends a radio-frequency pulse corresponding to aLarmor frequency to the RF transmitting coil 6 based on pulse-sequenceexecution data sent from the computing system 10. Specifically, thetransmitting unit 7 includes an oscillating unit, a phase selectingunit, a frequency converting unit, an amplitude modulating unit, and aradio-frequency power amplifying unit. The oscillating unit generates aradio-frequency signal of a resonance frequency unique to a subjectnucleus in the static magnetic field. The phase selecting unit selects aphase of the radio-frequency signal. The frequency converting unitconverts a frequency of the radio-frequency signal output by the phaseselecting unit. The amplitude modulating unit modulates amplitude of theradio-frequency signal output by the frequency converting unit inaccordance with, for example, a sinc function. The radio-frequency poweramplifying unit amplifies the radio-frequency signal output by theamplitude modulating unit. As a result of operation performed by theabove units, the transmitting unit 7 transmits a radio-frequency pulsecorresponding to a Larmor frequency to the RF transmitting coil 6.

The RF receiving coil 8 is arranged inside the gradient magnetic-fieldcoil 2, and receives a magnetic resonance signal irradiated from thesubject owing to an influence of the RF magnetic field. Upon receiving amagnetic resonance signal, the RF receiving coil 8 outputs the magneticresonance signal to the receiving unit 9.

The receiving unit 9 creates magnetic-resonance signal data based on themagnetic resonance signal output by the RF receiving coil 8 based onpulse-sequence execution data sent from the computing system 10. Uponcreating magnetic-resonance signal data, the receiving unit 9 sends themagnetic-resonance signal data to the computing system 10.

The computing system 10 performs total control of the MRI apparatus 100,data collection, image reconstruction, and the like. Specifically, thecomputing system 10 includes an interface unit 11, a data collectingunit 12, a data processing unit 13, a storage unit 14, a display unit15, an input unit 16, and a control unit 17.

The interface unit 11 is connected to the gradient magnetic-field powersource 3, the patient couch control unit 5, the transmitting unit 7, andthe receiving unit 9; and controls input and output of signals that aretransmitted or received between each of the connected units and thecomputing system 10.

The data collecting unit 12 collects magnetic-resonance signal data sentfrom the receiving unit 9 via the interface unit 11. Upon collectingmagnetic-resonance signal data, the data collecting unit 12 stores thecollected magnetic-resonance signal data into the storage unit 14.

The data processing unit 13 performs post-processing, i.e.,reconstruction processing, such as a Fourier transform, on themagnetic-resonance signal data stored in the storage unit 14, andcreates spectrum data or image data of a desired nuclear spin inside thesubject P.

The storage unit 14 stores therein magnetic-resonance signal datacollected by the data collecting unit 12, and image data created by thedata processing unit 13, with respect to each of the subject P.

The display unit 15 displays thereon various information, such asspectrum data or image data, under the control of the control unit 17. Adisplay device, such as a liquid crystal display, can be used as thedisplay unit 15.

The input unit 16 receives various instructions and information inputfrom an operator. As the input unit 16, input devices, for example,pointing devices, such as a mouse or a trackball, a selecting device,such as a mode switch, and a keyboard, can be used as required.

The control unit 17 includes a Central Processing Unit (CPU) and amemory, both of which are not shown, and totally controls the MRIapparatus 100.

As described above, a general configuration of the MRI apparatus 100according to the embodiment has been explained. According to the MRIapparatus 100 of the embodiment configured in this way, the computingsystem 10 causes the display unit 15 to display a time chart thatindicates timing with which a target scan position is collected, whatkind of prepulse to be applied, and in what order and how frequentlyeach prepulse is to be applied, thereby allowing an operator to confirmeasily influence on an image due to a change in scanning parameters.

Functions that the computing system 10 has are specifically explainedbelow. At first, a detailed configuration of the computing system 10according to the embodiment is explained below in detail with referenceto FIG. 2. FIG. 2 is a functional block diagram that depicts a detailedconfiguration of the computing system 10 according to the embodiment.FIG. 2 depicts a detailed configuration of the display unit 15, thecontrol unit 17, and the storage unit 14, and interrelations among theinterface unit 11, the storage unit 14, the display unit 15, the inputunit 16, and the control unit 17.

As shown in FIG. 2, the storage unit 14 stores therein particularlyexamination information 14 a. The examination information 14 a indicatesscanning conditions in accordance with the type of a scan among variousscans, and includes values of various scanning parameters included inthe scanning conditions, such as the type of a scan, the position of aslice, a slice thickness, the number of slices, and the like.

As shown in FIG. 2, the display unit 15 includes particularly ascanning-condition edit display unit 15 a, a positioning display unit 15b, and a time-chart display unit 15 c.

The scanning-condition edit display unit 15 a displays information aboutscanning conditions. Specifically, under the control of ascanning-condition edit/scan positioning unit 17 a, thescanning-condition edit display unit 15 a displays an area for inputtingand outputting information about a scanning condition with respect toeach of the scanning parameters, and a scanning-condition edit screenthat includes a user interface for receiving various operations from theoperator.

The positioning display unit 15 b displays a positioning image to be areference when determining the position of a slice to be scanned.Moreover, the positioning display unit 15 b displays a figure indicatinga slice region on the positioning image based on scanning conditions setby the operator. When a scanning condition is changed by the operator,the positioning display unit 15 b changes the position and/or the shapeof a figure indicating a slice region in a synchronized manner withdisplay of the scanning conditions performed by the scanning-conditionedit display unit 15 a.

The time-chart display unit 15 c displays a time chart created by thescanning-condition edit/scan positioning unit 17 a.

As shown in FIG. 2, the control unit 17 includes particularly thescanning-condition edit/scan positioning unit 17 a, a scanning-parameterlimit calculating unit 17 b, and a pulse-sequence execution-datacreating unit 17 c.

The scanning-condition edit/scan positioning unit 17 a receivesinformation about edit of a scanning condition and positioning of aslice. Moreover, the scanning-condition edit/scan positioning unit 17 acreates a time chart that indicates types and order of events to beexecuted when collecting magnetic-resonance signal data based on theexamination information 14 a created by the scanning-parameter limitcalculating unit 17 b, and causes the time-chart display unit 15 c todisplay the created time chart.

Specifically, to begin with, when receiving a display request for ascanning-condition edit screen 20 from the operator via the input unit16, the scanning-condition edit/scan positioning unit 17 a controls andcauses the scanning-condition edit display unit 15 a to display thescanning-condition edit screen 20.

Moreover, when receiving an operation of setting a value for a scanningparameter on the scanning-condition edit screen 20 from the operator viathe input unit 16, the scanning-condition edit/scan positioning unit 17a passes the set value to the scanning-parameter limit calculating unit17 b parameter by parameter of the scanning parameters. When a limitvalue of a scanning parameter is then returned from thescanning-parameter limit calculating unit 17 b, the scanning-conditionedit/scan positioning unit 17 a controls and causes thescanning-condition edit display unit 15 a to display the returned limitvalue onto the scanning-condition edit screen 20 parameter by parameterof the scanning parameters.

Moreover, when receiving a display request for a time chart from theoperator via the input unit 16, the scanning-condition edit/scanpositioning unit 17 a reads the examination information 14 a stored bythe storage unit 14, and creates a time chart that indicates types andsequential execution-order of events to be executed when collectingdata, based on the examination information 14 a that is read.

When creating the time chart, the scanning-condition edit/scanpositioning unit 17 a creates a time chart 30 such that time intervalsof the events to be executed are to be indicated. The scanning-conditionedit/scan positioning unit 17 a then controls and causes the time-chartdisplay unit 15 c to display the created time chart.

Display of a time chart conducted by the scanning-condition edit/scanpositioning unit 17 a is explained below in detail with reference toFIG. 3. FIG. 3 is a schematic diagram for explaining display of a timechart conducted by the scanning-condition edit/scan positioning unit 17a. FIG. 3 depicts an example of the scanning-condition edit screen 20displayed by the scanning-condition edit display unit 15 a.

As shown in FIG. 3, for example, the scanning-condition edit screen 20includes areas for displaying values each of which is set with respectto each of the scanning parameters, such as “repetition time (TR)”, “thenumber of slices”, “slice thickness”, and “the number of times ofsummation”. According to the scanning-condition edit screen 20, themaximum number of slices that can be scanned within a set repetitiontime is calculated by referring to other scanning conditions and otherinformation (for example, the weight of a patient and an RF transmissionpower) stored by the storage unit 14 as the examination information 14a. An example shown in FIG. 3 depicts a case of collecting atwo-dimensional spin-echo image by a multislice method, where six slicesare to be collected during a repetition time TR=500 milliseconds.

Moreover, the scanning-condition edit screen 20 includes buttons forreceiving various operations from the operator, for example, a presatbutton 21, an interleave button 22, and a sequence chart button 23 asshown in FIG. 3. The presat button 21 receives from the operator asetting request to set a presaturation pulse for suppressing signalsfrom irrelevant portions of a scan subject. The interleave button 22receives a reorder request to reorder a slice collection order within arepetition time. The sequence chart button 23 receives a display requestfor a time chart.

According to the scanning-condition edit screen 20, when the operatorpresses the sequence chart button 23 via the input unit 16, for example,the scanning-condition edit/scan positioning unit 17 a creates anddisplays the time chart 30 on which figures denoting collection of dataof six slices are sequentially arranged, as shown in the lower part ofthe FIG. 3. According to FIG. 3, “acq” denotes data collection, and “S1”to “S6” denote slice numbers from 1 to 6, respectively. The time chart30 indicates that data collection of each slice is performed in theorder of the slice numbers within the repetition time.

When the operator presses the presat button 21 on the scanning-conditionedit screen 20 via the input unit 16, the scanning-condition edit/scanpositioning unit 17 a controls and causes the scanning-parameter limitcalculating unit 17 b to recalculate the number of slices, and thenchanges display of the scanning-condition edit screen 20 and the timechart 30 based on a calculation result.

Specifically, when the operator presses the presat button 21 on thescanning-condition edit screen 20, the scanning-condition edit/scanpositioning unit 17 a controls and causes the scanning-parameter limitcalculating unit 17 b to recalculate the number of slices that can bescanned within a repetition time when a presaturation pulse is addedimmediately before data collection of each slice, and causes thescanning-condition edit screen 20 to display the recalculated number ofslices.

FIG. 4 is a schematic diagram for explaining display of the time chart30 when the presat button 21 is pressed. When the presat button 21 ispressed, the scanning-condition edit/scan positioning unit 17 a changesdisplay of the number of slices, for example, as shown in FIG. 4, fromsix to five.

Moreover, the scanning-condition edit/scan positioning unit 17 a changesdisplay of the time chart 30 displayed by the time-chart display unit 15c based on the number of slices recalculated by the scanning-parameterlimit calculating unit 17 b.

For example, the scanning-condition edit/scan positioning unit 17 achanges the number of figures denoting data collection indicated on thetime chart 30 to five from six as shown in the lower part of FIG. 4, andadds a figure “p” denoting a presaturation pulse immediately before eachof “S1” to “S5” denoting data collection along a single time axis.

In this way, as the scanning-condition edit/scan positioning unit 17 achanges display of the time chart 30 when the operator presses thepresat button 21, the operator can easily confirm visually a change in apulse sequence, a process of reduction in the number of slices, and anapplication frequency of presaturation pulses, when application of apresaturation pulse is added.

Moreover, when the operator presses the interleave button 22 on thescanning-condition edit screen 20 via the input unit 16, thescanning-condition edit/scan positioning unit 17 a causes the slicecollection order during a repetition time to be reordered by controllingthe scanning-parameter limit calculating unit 17 b, and then changesdisplay of the time chart 30 based on a result of the reordering.

FIGS. 5A and 5B are schematic diagrams for explaining display of thetime chart 30 when the interleave button 22 is pressed. As shown in theupper part of FIG. 5A, when the interleave button 22 is pressed, thescanning-condition edit/scan positioning unit 17 a reorders the slicecollection order displayed on the time chart 30 to the order of “S1”,“S3”, “S5”, “S2”, and “S4”, from the order of “S1”, “S2”, “S3”, “S4”,and “S5”.

Conventionally, a change in the slice collection order due to a changein scanning parameters cannot be easily confirmed. However, according tothe embodiment, as shown in FIG. 5A, it is clearly stated on the timechart 30 that the order of slice excitation is changed to collecteven-numbered slices after collecting odd-numbered slices first, so thatthe operator can easily confirm a change in the slice collection orderby comparing the time chart 30 with that in the previous state shown inthe lower part of FIG. 4.

Furthermore, according to the embodiment, the scanning-conditionedit/scan positioning unit 17 a is configured to synchronize displayonto a positioning image performed by the positioning display unit 15 band display of the scanning-condition edit screen 20 and the time chart30, event by event, thereby more clearly notifying the operator ofinfluence on an image due to a change in scanning conditions.

For example, FIG. 5B depicts an example that scan positions of thefollowing lateral cross sections are planned on a positioning image 40that is a sagittal section of the neck. According to FIG. 5B, squaresnumbered “1” to “5” indicate respective slice (slice region) positions.Slice 1 shown in FIG. 5B corresponds to slice S1 on the time chart 30shown in the lower part of FIG. 5A, and similarly, slice 2 shown in FIG.5B corresponds to slice S2 on the time chart 30. Similarly, slices 3, 4,and 5 shown in FIG. 5B correspond to slices S3, S4, and S5 on the timechart 30, respectively.

In this way, as the scanning-condition edit/scan positioning unit 17 adisplays slices on the time chart 30 and slices on the positioning image40 by associating them in accordance with respective slice numbers, theoperator can easily recognize that every other slice is excited from thehead side of a subject, subsequently, each slice in-between is excited.In other words, when there is interference between slices due todivergence from an optimal slice property, the operator can easilyrecognize that the order of excitation is changed to reduce theinterference.

Moreover, as shown in FIG. 5B, the scanning-condition edit/scanpositioning unit 17 a displays a figure P1 that indicates a position ofa presaturation pulse on the positioning image 40. Accordingly, theoperator can easily grasp a portion to be excited before obtaining eachslice data.

Additionally, when the operator specifies, for example, slice 3, on thepositioning image 40 via the input unit 16; the scanning-conditionedit/scan positioning unit 17 a highlights slice S3 on the time chart 30corresponding to slice 3. On the other hand, for example, when theoperator specifies slice S3 on the time chart 30 on the contrary, thescanning-condition edit/scan positioning unit 17 a highlights slice 3 onthe positioning image 40 corresponding slice S3.

In this way, as the scanning-condition edit/scan positioning unit 17 achanges display of a slice on the time chart 30 or the positioning image40 so as to indicate association between a slice on the time chart 30and a slice on the positioning image 40, thereby presenting spatialarrangement and temporal arrangement of data collection in an associatedmanner to the operator.

Returning to FIG. 2, the scanning-parameter limit calculating unit 17 bcalculates a limit value of a scanning parameter, and createsexamination information that indicates scanning conditions forcollection of magnetic-resonance signal data. Specifically, uponreceiving a value of a scanning parameter from the scanning-conditionedit/scan positioning unit 17 a, the scanning-parameter limitcalculating unit 17 b calculates a limit value of another scanningparameter that depends on the received scanning parameter.

The scanning-parameter limit calculating unit 17 b then returns thecalculated limit value of the scanning parameter to thescanning-condition edit/scan positioning unit 17 a, creates each timethe examination information 14 a indicating scanning conditions forcollection of magnetic-resonance signal data based on the received valueof the scanning parameter and the calculated value of the scanningparameter, and stores the examination information 14 a into the storageunit 14.

The pulse-sequence execution-data creating unit 17 c executes a scan byusing the examination information 14 a stored in the storage unit 14.Specifically, when receiving a start instruction to start a scan fromthe operator via the input unit 16, the pulse-sequence execution-datacreating unit 17 c creates pulse-sequence execution data 17 d based onscanning conditions stored in the storage unit 14 as the examinationinformation 14 a. The pulse-sequence execution-data creating unit 17 cthen causes the gradient magnetic-field power source 3, the transmittingunit 7, and the receiving unit 9 to execute the scan by sending thepulse-sequence execution data 17 d via the interface unit 11.

A process procedure of time-chart display performed by the MRI apparatus100 according to the embodiment is explained below. FIG. 6 is aflowchart of a process procedure of time-chart display performed by theMRI apparatus 100 according to the embodiment.

As shown in FIG. 6, according to the MRI apparatus 100, when receiving adisplay request to display the scanning-condition edit screen 20 fromthe operator, the scanning-condition edit/scan positioning unit 17 acontrols and causes the scanning-condition edit display unit 15 a todisplay the scanning-condition edit screen 20 (Step S101), and receivessetting of scanning conditions (Step S102).

When the scanning conditions are then set on the scanning-condition editscreen 20 by the operator, the scanning-parameter limit calculating unit17 b creates the examination information 14 a based on the set scanningconditions (Step S103).

After that, if the operator presses the sequence chart button 23 on thescanning-condition edit screen 20 (Yes at Step S104), thescanning-condition edit/scan positioning unit 17 a creates the timechart 30 based on the examination information 14 a created by thescanning-parameter limit calculating unit 17 b, and then controls andcauses the time-chart display unit 15 c to display the time chart 30that is created (Step S105).

If the operator presses the presat button 21 on the scanning-conditionedit screen 20 (Yes at Step S106), the scanning-parameter limitcalculating unit 17 b recalculates the number of slices (Step S107), andthe scanning-condition edit/scan positioning unit 17 a changes displayof the time chart 30 based on the recalculated number of slices (StepS108).

If the operator presses the interleave button 22 on thescanning-condition edit screen 20 (Yes at Step S109), thescanning-parameter limit calculating unit 17 b reorders the slicecollection order (Step S110), and changes display of the time chart 30based on the reordered slice collection order (Step S111).

As described above, according to the embodiment, the scanning-parameterlimit calculating unit 17 b creates the examination information 14 athat indicates scanning conditions for collection of magnetic-resonancesignal data based on a value of a scanning parameter set by theoperator; and the scanning-condition edit/scan positioning unit 17 acreates the time chart 30 that indicates types and sequentialexecution-order of events to be executed when collectingmagnetic-resonance signal data based on the examination information 14 acreated by the scanning-parameter limit calculating unit 17 b, andcauses the time-chart display unit 15 c to display the time chart 30.Accordingly, the operator can easily confirm influence on an image dueto a change in the scanning parameters.

Although display of the time chart 30 in a case where a two-dimensionalspin-echo image is collected according to the multislice method isexplained in the above embodiment with reference to FIGS. 3 to 5B, thedisplay style of the time chart 30 is not limited to those shown inFIGS. 3 to 5B, and other display styles appropriate to respective scantypes can be used. Respective modifications of the time chart 30appropriate to other scan types are explained below. The followingmodifications are explained mainly about processing performed by thescanning-condition edit/scan positioning unit 17 a.

(1) Coronary Angiography Combined with Electrocardiogram (ECG) Gating

Display of a time chart for coronary angiography combined with ECGgating is explained below. According to coronary angiography combinedwith ECG gating, various prepulses are usually applied prior to actualdata collection: for example, a prepulse for giving T2 contrast, datacollection for compensating motion by detecting body movement, apresaturation pulse for suppressing irrelevant signals outside a regionof interest, a pulse for suppressing a fat signal, and a dummy pulse forhelping to reach a steady state.

When the examination information 14 a read from the storage unit 14indicates scanning conditions for coronary angiography combined with ECGgating, the scanning-condition edit/scan positioning unit 17 a causesthe time-chart display unit 15 c to display a time chart on which theabove prepulses are displayed.

FIG. 7 is a schematic diagram of an example of a time chart for coronaryangiography combined with ECG gating. As shown in FIG. 7, for example,the scanning-condition edit/scan positioning unit 17 a causes thetime-chart display unit 15 c to display a time chart 130 on whicharranged before “acq” denoting data collection are a figure “T2 prep”denoting a prepulse for giving T2 contrast, a figure “Nav” denoting datacollection for compensating motion by detecting body movement, a figure“p” denoting a presaturation pulse for suppressing irrelevant signalsoutside a region of interest, a figure “F” denoting a pulse forsuppressing a fat signal, and a figure “D” denoting a dummy pulse forhelping to reach a steady state.

The coronary angiography combined with ECG gating is performedsynchronously with an electrocardiographic waveform of a subject, sothat each event occurs consistently in accordance with a relative timefrom an R wave. As shown in FIG. 7, the scanning-condition edit/scanpositioning unit 17 a conducts display of a simulatedelectrocardiographic waveform together on the time chart 130, andfurther conducts display of a time of R-R interval (“R-R=950” shown inFIG. 7) on the simulated electrocardiographic waveform. Moreover, thescanning-condition edit/scan positioning unit 17 a conducts display of adelay time from an R wave until a prepulse for giving T2 contrast(“Td=200” shown in FIG. 7).

In this way, as the scanning-condition edit/scan positioning unit 17 aconducts display of an electrocardiographic waveform, a time of R-Rinterval, and a delay time from an R wave as well as the time chart 130,the operator can easily confirm visually a state of producing a pulsesequence that each prepulse is applied for a certain period after 200milliseconds of a delay time from an R wave, subsequently a dummy pulseis applied, and then data collection is performed during a time phasecorresponding to a diastole.

According to the coronary angiography combined with ECG gating, thereare several factors relevant to the image quality: for example, datacollection is to be performed during a diastole in which cardiac motionis relatively inactive; a data collection time within one heart beatshould be set as short as possible within an allowable range in thetotal scanning time; and a fat suppression pulse “F” and data collection“Nav” for detecting motion are to be executed with timing closely todata collection “acq” as much as possible.

Conventionally, it is difficult for an operator to understand whetherscanning parameters of the factors are appropriately set only based on ascanning-condition setting screen. However, according to the embodiment,an electrocardiographic waveform, a time of R-R interval, and a delaytime from an R wave until a prepulse for giving T2 contrast aredisplayed as well as the time chart 130, accordingly, the operator caneasily determine whether scanning parameters are appropriately set.

Furthermore, the scanning-condition edit/scan positioning unit 17 a canbe configured to display a part specified by the operator on the timechart 130 in an enlarged manner in detail. A chart enlarged view 131shown in FIG. 7 depicts an enlarged view of the data collection part“acq”, and indicates that “acq” includes collection of four continuousfield echoes.

Usually, more detailed information about a pulse sequence than the chartenlarged view 131 shown in FIG. 7 is not necessarily required foroperation of setting scanning conditions. However, thescanning-condition edit/scan positioning unit 17 a can be configured toconduct further enlarged display of the chart enlarged view 131 in moredetail (displaying a pulse sequence type by type of a pulse, forexample, a radio-frequency pulse, a slice-selective gradientmagnetic-field pulse, a phase-encoding gradient magnetic-field pulse,and a frequency-encoding gradient magnetic-field pulse). In such case,the scanning-condition edit/scan positioning unit 17 a controls to whatextent detailed information is to be disclosed, for example, dependingon a qualification of an operator.

(2) Imaging by Segmented Field Echo Method

Display of a time chart for imaging by segmented field echo is explainedbelow, according to which a k-space is divided into a plurality of unitscalled segment, and application of a prepulse and ECG gating areperformed segment by segment.

Specifically, when the examination information 14 a read from thestorage unit 14 indicates scanning conditions for imaging by thesegmented field echo, the scanning-condition edit/scan positioning unit17 a causes the time-chart display unit 15 c to display a time chart onwhich figures each indicating a fat suppression prepulse and figureseach indicating a segment are alternately arranged.

FIG. 8 is a schematic diagram of an example of a time chart for imagingby the segmented field echo method, and depicts a time chart when fatsuppression prepulses are used in combination. As shown in the upperpart of FIG. 8, for example, when the number of segments are two, thescanning-condition edit/scan positioning unit 17 a conducts display of atime chart 230 on which “F” denoting a fat suppression prepulse, afigure “Seg 1” denoting a first segment, “F” denoting a fat suppressionprepulse, and a figure “Seg 2” denoting a second segment are arranged inorder.

For example, when the operator changes the number of segments to eight,the scanning-condition edit/scan positioning unit 17 a increases figureseach denoting a segment to eight as shown in the lower part of FIG. 8,and changes display of the time chart 230 such that each of the fatsuppression prepulses “F” is arranged immediately before each of thefigures “Seg 1” to “Seg 8” denoting segments.

In this way, as the scanning-condition edit/scan positioning unit 17 achanges display of the time chart 230 based on the number of segmentsset by the operator, the operator can easily confirm that as a result ofan increase in the number of fat suppression pulses, a total scanningtime is increased even if the other scanning conditions than the numberof segments remain the same, and a fat suppression effect is improvedbecause of an increase in the frequency of the fat suppression pulses.

Such influence given to the scanning time and the image quality becauseof a change in the scanning conditions cannot be explained unlessindicating timing of the pulse sequence. Such influence is usuallydescribed in an operation manual of a device. However, according to theembodiment, a change in the scanning conditions is displayedsimultaneously upon changing a scanning condition when editing thescanning conditions as described above. Accordingly, the operator canunderstand influence on the image quality more thoroughly.

(3) Angiography by Arterial Spin Labeling (ASL)

Display of a time chart for angiography by ASL is explained below. Amethod called Time Spatial Labeling Inversion Pulse (Time-SLIP), whichis one of ASL methods, is explained below. The Time-SLIP is a method ofsetting a region of a selective inversion pulse separately from a Fieldof View (FOV) in order to render a specific blood vessel selectively.

Specifically, when the examination information 14 a read from thestorage unit 14 indicates scanning conditions for imaging by Time-SLIP,the scanning-condition edit/scan positioning unit 17 a causes thetime-chart display unit 15 c to display a time chart on which aninversion pulse and data collection are displayed.

FIGS. 9A and 9B are schematic diagrams of an example of a time chart forimaging by Time-SLIP. FIG. 9A depicts a time chart when rendering onlyarterial blood flowing into the FOV by collecting data after aninversion pulse is applied and then a certain time elapses. Moreover,according to the example shown in FIG. 9A, a presaturation pulse isapplied additionally to another region for suppressing a signal fromvenous blood flowing in during the same period.

As shown in FIG. 9A, for example, the scanning-condition edit/scanpositioning unit 17 a conducts display of a time chart 330 on which afigure “IR” denoting an inversion pulse, and a figure “p” denoting apresaturation pulse are arranged before “acq” denoting data collection.Moreover, the scanning-condition edit/scan positioning unit 17 aconducts display of a simulated electrocardiographic waveform on thetime chart 330 in combination, and further conducts display of a time ofR-R interval (“R-R=900” shown in FIG. 9A) and a time from the inversionpulse until the data collection (“TI=600” shown in FIG. 9A) on thesimulated electrocardiographic waveform.

When rendering a specific blood vessel by ASL, scanning conditions needto be appropriately set by totally considering running and anapproximate blood-flow velocity of the blood vessel, and timing andposition of each pulse. According to the embodiment, anelectrocardiographic waveform, a time of R-R interval, and a time froman inversion pulse until data collection are displayed as well as thetime chart 330, accordingly, the operator can easily determine whetherscanning parameters are appropriately set.

When conducting display of the figure “IR” denoting an inversion pulse,the figure “p” denoting a presaturation pulse, and the figure “acq”denoting data collection on the time chart 330, the scanning-conditionedit/scan positioning unit 17 a can be configured to conduct display offigures in colors, tones, or patterns, such as crosshatching, differentfrom type to type of pulses. The scanning-condition edit/scanpositioning unit 17 a can then conduct display of figures (rectangles inthis case) on a positioning image 340 in the same color, or the sametone, or the same pattern, as that denoting each pulse as shown in FIG.9B (according to an example shown in FIG. 9B, types of lines ofrectangles are varied instead of varying colors, tones, or patterns).Accordingly, the operator can easily understand association betweenspatial position and temporal order of each pulse.

(4) Display of Position in k-Space of Collected Data

Influences given onto an image that an MRI apparatus obtains byperforming Fourier transformation on collected data vary depending on aposition of the collected data in an actual space (called k-space).Specifically, it is well known that a signal arranged in the vicinity ofthe center of a k-space, i.e., a low-frequency region gives influence onthe contrast of an image, and contours of the image are influenced bysignals arranged in an outer side of the k-space, i.e., aradio-frequency region.

Therefore, the order of collecting data arranged on a k-space issometimes highly relevant for imaging by an MRI apparatus in some cases.For this reason, the scanning-condition edit/scan positioning unit 17 acan be configured to cause the time-chart display unit 15 c to display aposition of collected data in a k-space together with a time chart.

FIGS. 10A, 10B, and 10C are schematic diagrams of an example of a timechart when displaying the position of collected data in a k-space. FIG.10A depicts an example of a time chart for a so-called dynamic scan,according to which scans are continuously repeated after a contrastagent is injected from a vein.

Specifically, when the examination information 14 a read from thestorage unit 14 indicates scanning conditions for a dynamic scan, thescanning-condition edit/scan positioning unit 17 a causes the time-chartdisplay unit 15 c to display a time chart indicating time points ofexecution timing of continuous scans, i.e., data collection.

For example, as shown in FIG. 10A, the scanning-condition edit/scanpositioning unit 17 a conducts display of a time chart 430 on whichfigures “ph. 1” to “ph. 5” denoting the width of data collection in fivetime phases are arranged together with time points of starting datacollection. When displaying “ph. 1” to “ph. 5”, the scanning-conditionedit/scan positioning unit 17 a conducts display of parts denotingcollection of data included in a predetermined proportion (for example,25%) from the center of the k-space, in a color, or a tone, or a patterndifferent from the other parts.

The contrast of an image obtained through Fourier transformation isdetermined in accordance with timing of collecting data in the center ofthe k-space. Therefore, recognition of a time point of collecting datain the center of the k-space from the start of the injection of acontrast agent is highly relevant similarly to recognition of a timepoint of whole data collection in each time phase, in order to obtain animage with an appropriate contrast.

According to the embodiment, because “ph. 1” to “ph. 5” each denotingthe width of data collection are displayed every time phases in adynamic scan together the time, and the position of collected data inthe k-space is indicated to each of “ph. 1” to “ph. 5”. Accordingly, itcan be easily confirmed whether scanning conditions required to obtainan image with an appropriate contrast are correctly set.

Although FIG. 10A depicts an example of displaying collected datadivided into two, namely, a region within 25% from the k-space center,and the other region, the number of regions to be divided are notlimited to two, and a region can be divided into more. In such case,display of a figure denoting the width of data collection turns to moredetailed one, for example, as shown in FIG. 10B. FIG. 10C depicts theposition of collected data in the k-space indicated by the figure shownin FIG. 10B.

Although explained in the above embodiments is a case where a time chartis displayed in an edit process of scanning conditions, the presentinvention is not limited to this. For example, according to animplementation of the apparatus, if examination information is renewedwhen creating pulse-sequence execution data, it can be configured suchthat a time chart can be displayed after the pulse-sequence executiondata is created.

As described above, the magnetic resonance imaging apparatus and thescanning-condition setting method according to the embodiments of thepresent invention are useful for confirming influence on an image due toa change in scanning conditions, and particularly suitable whenconfirming a sequential order of events to be executed when collectingdata.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

What is claimed is:
 1. A magnetic resonance imaging apparatuscomprising: a processor that: creates examination information thatrepresents a scanning condition for collection of data indicating aninside of a subject, based on a value of a scanning parameter set by anoperator; and creates and causes a display to display a time chart thatindicates a type and a sequential execution order of an event to beexecuted when performing the collection of data, based on the createdexamination information, wherein the processor conducts display ofinformation indicating a position of collected data in a k-spacetogether with display of the time chart.
 2. A scanning-condition settingmethod of a magnetic resonance imaging apparatus, comprising: creatingexamination information that represents a scanning condition forcollection of data indicating an inside of a subject based on a value ofa scanning parameter set by an operator; and creating and causing adisplay to display a time chart indicating a type and a sequentialexecution order of an event to be executed when performing thecollection of data, based on the created examination information.wherein the causing the display to display the time cart comprisesconducting display of information indicating a position of collecteddata in a k-space together with display of the time chart.